1. Field of the Invention
The present invention relates to a method for installing radiator elements arranged on different planes and an antenna having the radiator elements.
2. Description of the Related Art
Extensive research has recently been conducted on small, lightweight antennas for use in Base Stations (BSs) or relays in a mobile communication system. A dual-band dual-polarization antenna is under development, in which a second radiator of a high frequency band (e.g. 2 GHz) is stacked on a first radiator element of a low frequency band (e.g. 800 MHz).
In such an antenna, for example, patch-type or dipole-type second radiator elements may be overlapped on patch-type first radiator elements. These stacked first and second radiator elements are arranged on a reflective plate at intervals to form a radiator element array of a first frequency band. In addition, second radiator elements are installed between the stacked first and second radiator elements on the reflective plate in order to form a radiator element array of a second frequency band. This layout contributes to antenna miniaturization and achieves antenna gain.
However, because the second radiator elements stacked on the first radiator elements and the independently installed second radiator elements are on different planes, a phase difference may be produced when a signal of the second frequency band is radiated.
To avert the problem, the independently installed second radiator elements may be installed high by means of an auxiliary device so that the independently installed second radiator elements are even with the second radiator elements stacked on the first radiator elements. However, this scheme adversely affects radiation of the first radiator elements of the first frequency band, thereby degrading radiation characteristics of a first frequency-band signal.
At present, therefore, a technique for narrowing the difference between the planes of the independently installed second radiator elements and the second radiator elements stacked on the first radiator elements is adopted, although affecting radiation of the first radiator elements of the first frequency band within an allowed range.